This study examines the risk factor profile, in-hospital course and outcome of 337 women and 643 men admitted with a first episode of acute coronary insufficiency or myocardial infarction. The women were older than the men and had a risk factor profile dominated by hypertension and hypercholesterolemia rather than smoking. Women had a higher rate of unstable angina than did men after adjustment for age distribution. Women with acute infarction showed a higher rate of complications, which was associated with their greater age. They had a higher in-hospital mortality rate (12.6%) than did men (6.6%, p = 0.002). A logistic regression was used to adjust mortality and complication rates for differences in age between the sexes. When this was done, women and men had similar in-hospital prognoses. It is concluded that differences in risk factor profile may result in differences between the sexes in the expression of acute coronary heart disease, but that gender as such does not exert an independent influence on short-term prognosis in this disease.